First of all, its not a big problem.
I have created a custom registration form. For the username field I have used the sanatizer api before storing the username in the database.
$username is the variable from the form input after submit (Post)
I sanatize it like this:
In the guidelines there is the following statement:
So far so good, but sanatizing the username value changes all big letters [A-Z] to small letters [a-z]. So it doesnt allow big letters in the username. It is not a big deal, but big letters should be allowed according to the statement.
Does anyone made the same experience.
PS: I use the latest stable version of PW.
Addition: it also changes the "@" into "-" .